A known type of a fuel cell for generating electricity by utilizing electrochemical reaction between hydrogen and oxygen is a solid oxide fuel cell (hereinafter may be referred to as “SOFC”) which includes electrolyte layers containing a solid oxide. In general, an SOFC is used in the form of a fuel cell stack including a plurality of interconnector-fuel cell unit cell composite bodies (hereinafter may be referred to simply as “composite bodies”) that are disposed in a predetermined direction (hereinafter referred to as a “first direction”). Each composite body includes a unit cell of a fuel cell (hereinafter may be referred to simply as a “unit cell”) and an interconnector. The unit cell includes an electrolyte layer, a cathode, and an anode such that the cathode and the anode face each other in the first direction and the electrolyte layer intervenes between these electrodes. The interconnector is disposed on the anode side of the unit cell and has a through hole defining a fuel gas flow channel.
In a known technique relating to such a fuel cell stack, a sealing member forming the aforementioned fuel gas flow channel is disposed between a surface (hereinafter referred to as a “first surface”) of the interconnector of a first composite body (the first surface is opposite the surface of the interconnector facing the anode) and a second composite body disposed so as to face the first surface, thereby sealing a cathode chamber facing the cathode of the second composite body (see, for example, Patent Document 1).
In another known technique, a coating is formed on the first surface of an interconnector opposite the surface facing the anode for preventing diffusion of Cr (chromium) contained in the interconnector (see, for example, Patent Document 2).